<img src="/img/tutorial/body-fields/image02.png">

## Technical Details

/// tip

If you are already using **FastAPI** version **0.99.0 or above**, you can probably **skip** these details.

They are more relevant for older versions, before OpenAPI 3.1.0 was available.

You can consider this a brief OpenAPI and JSON Schema **history lesson**. 🤓

///

/// warning

  val mappingsBuffer = StringBuilder()
  val sectionIndexBuffer = Buffer()

  var previousMappedRanges: List<MappedRange>? = null

  for ((section, sectionMappedRanges) in sections) {
    // Skip sequential ranges when they are equal.
    if (sectionMappedRanges == previousMappedRanges) continue
    previousMappedRanges = sectionMappedRanges

    val sectionOffset = rangesBuffer.size.toInt() / 4

    // Section prefix.

	metacacheBlockSize = 5000

	// metacacheSharePrefix controls whether prefixes on dirty paths are always shared.
	// This will make `test/a` and `test/b` share listings if they are concurrent.
	// Enabling this will make cache sharing more likely and cause less IO,
	// but may cause additional latency to some calls.
	metacacheSharePrefix = false
)

//go:generate msgp -file $GOFILE -unexported

It is also built to work as a future reference so you can come back and see exactly what you need.

## Run the code

All the code blocks can be copied and used directly (they are actually tested Python files).

To run any of the examples, copy the code to a file `main.py`, and start `fastapi dev` with:

<div class="termy">

```console

		return w.Flush()
	}
	return nil
}

func (s *XdsStatusWriter) setupStatusPrint(drs map[string]*discovery.DiscoveryResponse) (*tabwriter.Writer, []*xdsWriterStatus, error) {
	// Gather the statuses before printing so they may be sorted
	var fullStatus []*xdsWriterStatus
	mappedResp := map[string]string{}
	w := new(tabwriter.Writer).Init(s.Writer, 0, 8, 5, ' ', 0)
	_, _ = fmt.Fprintln(w, "NAME\tCLUSTER\tCDS\tLDS\tEDS\tRDS\tECDS\tISTIOD\tVERSION")

        // Failed to get attributes; we don't know the size.
        return Optional.absent();
      }

      // Don't return a size for directories or symbolic links; their sizes are implementation
      // specific and they can't be read as bytes using the read methods anyway.
      if (attrs.isDirectory() || attrs.isSymbolicLink()) {
        return Optional.absent();
      }

      return Optional.of(attrs.size());
    }

public final class CustomTrust {
  // PEM files for root certificates of Comodo and Entrust. These two CAs are sufficient to view
  // https://publicobject.com (Comodo) and https://squareup.com (Entrust). But they aren't
  // sufficient to connect to most HTTPS sites including https://godaddy.com and https://visa.com.
  // Typically developers will need to get a PEM file from their organization's TLS administrator.

  protected abstract Object handleInvocation(Object proxy, Method method, @Nullable Object[] args)
      throws Throwable;

  /**
   * By default delegates to {@link Object#equals} so instances are only equal if they are
   * identical. {@code proxy.equals(argument)} returns true if:
   *
   * <ul>
   *   <li>{@code proxy} and {@code argument} are of the same type

                  ListFeature.SUPPORTS_SET)
              .createTestSuite());
    }
    return suite;
  }

  // Test generators.  To let the GWT test suite generator access them, they need to be
  // public named classes with a public default constructor.

  public static final class BytesAsListGenerator extends TestByteListGenerator {
    @Override
    protected List<Byte> create(Byte[] elements) {

                  ListFeature.SUPPORTS_SET)
              .createTestSuite());
    }
    return suite;
  }

  // Test generators.  To let the GWT test suite generator access them, they need to be
  // public named classes with a public default constructor.

  public static final class LongsAsListGenerator extends TestLongListGenerator {
    @Override
    protected List<Long> create(Long[] elements) {